Fibre reinforced plastic (FRP) boat hulls conventionally have a smooth outer gelcoat layer and a structural layer made up of fibres, usually glass fibres, embedded in a resin, most usually a polyester resin. In some cases a foam or timber core is encapsulated between two reinforced fibre layers. The gelcoat and resin are initially liquids which are mixed with a hardener (catalyst) and applied within a mould in liquid state. After application, the liquids cure to the solid state.
After prolonged exposure to a marine environment, a number of boat hulls are found to suffer blistering which appears on the outer gelcoat surface. It appears that this is caused by a build up of fluid between the gelcoat layer and the fibre/resin layer. The damage can result from one or more of the following: water penetration; degradation reactions resulting from water penetration; deterioration resulting from faulty manufacture; deterioration resulting from faulty materials used in the moulding process; deterioration resulting from failed bonding or de-lamination of foam or timber cores; de-lamination of the moulding. The symptoms of such damage are often attributed to osmosis.
A layer of antifouling paint is usually applied to the gelcoat layer. The antifouling paint comprises substances that prevent or hinder the attachment of algae, microorganisms, barnacles etc, to the lower hull; this is necessary because foreign elements attached to the lower hull hinder the flow of water along the hull, so worsening the nautical characteristics (speed and maneuverability) of the boat.
Regardless of the surface finish selected, it is common to all fibreglass boats or other watercraft that once in service, surfaces are either totally immersed in or partially exposed to water. In some cases, the water may never completely be removed and remains in contact with the outside surfaces of the watercraft at all times. This inevitably creates a two-fold problem. The first is that the water itself is a harsh solvent capable of dissolving any water soluble material (WSM) and hydrolysing any of the water soluble components used in manufacture of the watercraft.
The second problem is that water, particularly saltwater is an extremely corrosive environment.
The salts present in a marine environment eventually cause bleaching and degradation of the watercraft surface. Over time, there are usually clear signs of fading and deterioration of the watercraft surface which significantly detracts from the aesthetic appearance of the craft. Fading and deterioration problems are increased by a variety of other factors such as:
a) exposure to UV light;
b) neglect and mismanagement of the watercraft;
c) elevation of water temperature.
Despite these problems, consumer expectations demand a product which can withstand degradation and importantly, retain the original colour for extended periods of time and without necessitating costly and time consuming stripping and refurbishing of the watercraft surface or even replacement of the watercraft itself, which are the only permanent and consumer acceptable remedies once significant degradation of the watercraft surface has occurred. Similarly, manufacturers of watercraft, who generally provide some degree of guarantee with watercraft, do not wish to become liable for repair or replacement if the watercraft surface cannot withstand degradation for a prescribed period of time.
Since the problem of surface degradation, including colour fading, is such a widespread problem, there have been various attempts to remedy or at least alleviate the problem. Such remedies include producing watercraft in colours such as white, creams or very pale blue colours that simply show only minimal effects of fading. The unfortunate outcome of such a remedy is that colour and finishing options then become severely limited.
Some success has been achieved by the application of the colour and decorative surface finish in a polyester gelcoat, the gelcoat having some UV resistant properties. However, although known gelcoats are able to offer a certain degree of resistance and longevity to the surface appearance, after about 6 to 10 years, the surface finish pigment inevitably starts to fade and the appearance of the surface of the watercraft becomes compromised and looks washed out.
Further, whilst it may at first seem a viable solution to protect the aesthetic, particularly the colour, qualities of the watercraft surface with the application of an additional protective or barrier layer, to date no such application has been successful in the unique circumstances of watercraft, where the watercraft surface is subject to prolonged periods of exposure to an aqueous environment.
There is therefore a need for a product which can prevent discolouration and degradation of the watercraft surface finish without compromising the availability of selection of colours and finishes.